00012-medium-chainable-options.ts

// ============= Test Cases =============
import type { Alike, Expect } from './test-utils'

declare const a: Chainable

const result1 = a
  .option('foo', 123)
  .option('bar', { value: 'Hello World' })
  .option('name', 'type-challenges')
  .get()

const result2 = a
  .option('name', 'another name')
  // @ts-expect-error
  .option('name', 'last name')
  .get()

const result3 = a
  .option('name', 'another name')
  // @ts-expect-error
  .option('name', 123)
  .get()

type cases = [
  Expect<Alike<typeof result1, Expected1>>,
  Expect<Alike<typeof result2, Expected2>>,
  Expect<Alike<typeof result3, Expected3>>
]

type Expected1 = {
  foo: number
  bar: {
    value: string
  }
  name: string
}

type Expected2 = {
  name: string
}

type Expected3 = {
  name: number
}

// ============= Your Code Here =============
type Chainable<T = {}> = {
  option<K extends PropertyKey, V>(
    key: K extends keyof T ? (V extends T[K] ? never : V) : K,
    value: V
  ): Chainable<Omit<T, K> & Record<K, V>>
  get(): T
}